Propeller, pump, or fan



V july 29, 1930.

E. s. G. REEs PROPELLER, PUMP, OR FAN Filed Oct. 17. 1927 3 Sheets-Sheet 1 A ,Rye/far .Einwand/5. 2268.5 (56 Mam@ July 29',- 1930. E. s. G. REEs PROPELLER, PUMP, OR FAN Filed Oct. 17. 1927 3 Sheets-Sheet 2 &

July 29, 1930. E. s. G. REEs PROPELLER, PUMP, OR FAN Filed Oct. 1'7, 1927 3 Sheets-Sheet 3 J. fw

Patented July 29, 1930 PATENT oFElcE EDMUND SCOTT GUSTAVE BEES, OF OAKEN, ENGLAND rnoPELLnn, PUMP, on, FAN

Application led October 17, 1927, Serial No. 226,699, and in Great Britain October 19, 1926.

This invention vrelates to impellers for pumps or fans, and turbine rotors driven by compressible and incompressible fluids.

A principal feature of the invention resides in the formation of the blades of the rotary element Ain 'such manner that they will impart movement to the still fluid surroundlng them, more by reason of suction of the liuid around the edge and along the rear face of 1o the blade, than by any thrust of the front face of the blade.

. -The rotor or impeller is multibladed and preferably has as many as five or six blades, or yeven considerably more, which are wrapped around a central boss to form channels into which the surrounding fluid is centripetally drawnby reason of the configuration of the blades and the relation of the pitch of the blades and the area ofthe iuid channels along their length.

The rotor or impeller blades are formed with a thickened or bulbous edge preferably of ogival cross section. The edge of each blade curves backwardly with respect to the direction of rotation. The edge of the blade may be wholly or in art in the periphery of an imaginary cylin er or cone enveloping the disc area of the rotor. f e

The channels between the blades are of in- 3o creasing depth from front to rear, at any rate over the forward part of their length, the remainder of their length, in the case of a pump impeller, being usually of uniform depth, while, where the discharge velocity is to be as small as possible, the final portion of their length is of increasing depth and the pitch of the blades may be diminished over this part. The varied depth of the channels may be providedfor by variation of the disc area of the impeller, or the disc area may be constant and the depth of the channels may be varied by suitable shaping of the boss on which the blades are mounted.

The function of the leadingportion of the blade is mainly to establish a centripetal How of the surrounding fluid towards the boss so as to fill the channel, While the function of the remaining portion is mainly to impart a rearward flow to thecontents of the filled channel, the ogival section of the edge of the blade along this part being usually desirable, but not always necessary.

While the depth of channel may increase along its whole length from front to rear, there is preferably an intermediate portion of uniform depth, and the front portion of the blade is made of increasing pitch so that the fluid is picked up efliciently thereby, the final pitch of this front portion being continued along the length of the intermediate part of the blade to correspond with the intermediate uniform part of the channel, while the remainder of the blade is of reduced pitch to slow down the fluid before it leaves the impeller.

A pump impeller constructed .according to the present invention is thus an absolutely open-bladed unshrouded structure. It is mounted to revolve Within a fixed casing or inlet tank of appreciable capacity and the stream or flume discharged from the impeller is preferably directed through a ring of fixed deflector blades into an annular expanding channel or other suitable diffuser deviceto convert the velocity of the stream into pressure. When the delivery valve of the pump is closed, the action of the impeller blades is merely to establish a local annular swirl or ring vortex vin a part of the mass of water within the casing and little power is wasted.

Another result of the construction described is that the impeller stream or flume can be confined Within the periphery of an lmaginary cylinder or annulus having such an area as to ensure that the jet or flume will be a solid cylindrical or annular stream of uniform velocity at all points on any given transverse section.

As an additional expedient for combating cavitation in the case of hydraulic impellers, means may be provided for conveying air to the region of lowest pressure in which cavitation is liable to be set up. For example, air

may be led through a control valve operating at a predetermined pressure to the boss of the impeller and thence through the ogival rib along the edge of each blade, both of which may be made hollow for this purpose, and therefrom distributed'over the surface of the l blades or any parts thereof by suitable ducts and openings. Or a by-pass circuit may be established by connecting a hollow core of the diffuser tube forming an extension of the deflector ring with the highest point of the suction side of the pump, thereby allowing air to be sucked in throu h the opening between the fixed ring of deectors and the discharge end of the impeller to the region of lowest pressure in the Hume.

ln the accompanying drawings Fig. l is a longitudinal section of a diagrammatic pump impeller or rotor, Fig. la being an elevation of saine looking in the direction of the arrow with the blades and boss shown in section in dotted lines, and Fig. lb is a development showing the relation of three successive blades; Fig. 2 is a longitudinal section of a rotary pump embodying one form of the improved impeller, and Fig. 2a is a detail View showing a. part in cross section and development Fig. 3 is. a 4view of a pump correspondlng with Fig. 2 showing a. modified construction of impeller; Figs. 4 and a are diagrammatie views showing a pump impeller discharging radially outwards into a volute diffuser; Figs. 5, 5a and 5b are respectively a longitudinal section, and side and end eleva tions of a construction of impeller or rotor comprising a separately formed impeller blade ring; Figs. 6, 6a and 6b are views corresponding with Figs. 5, 5B and 5b showing a modified construction of rotor or impeller; and Fig. 7 is an end elevation showing a modified construction of pump impeller.

It will be seen that, by reason of the configuration of the blades or of the boss around which they are wra pcd spiral fashion, the channel or passage etween adjacent blades increases in depth along its length, at any rate along the forward portion of its length. This characteristic is plainly seen from the diagrammatic representation of an impeller or rotor shown in Figs. 1--1b. In Fig. 1 there is shown one method which may be adopted for achieving a varying depth of channel for' the passage of the Huid. In the construction therein shown in full lines the disc area of the impeller is kept constant, and the boss B around which the blades A are spirally wrapped is so shaped as to give the appropriate gradations to the depth of the channel between the blades. It will be seen that this channel increases in depth along its front portion and that then comes an intermediate portion of substantially uniform depth. the rear portion again increasing in depth. That portion of the blade edge which extends along the deepening front part of the channel is made of increasing pitch, as shown in Fig. l", the intermediate part ofthebladecorresponding with that portion of the channel which is of substantially uniform depth being of uni form pitch, while the remainder of the blade is of decreasing pitch towards the rear. The

result of this variation of pitch in accordance with the variation of depth of channel is that, while the forward portion of the blade functions to draw surrounding fluid centripetally towards the boss so as to fill the channelsbetween adjacent blades, the intermediate portion of the blades functions merely to give a rearward Velocity to the fluid lilling the channel, and the rearward portion of the blades, in conjunction with the increasing depth of channel, functions to reduce the velocity of the fluid.

If the apparatus were to be used as a pump impeller the last or rearward portion would be omitted. and the channel would consistof a front or inlet portion of increasing cross section,'while the remainder of the channel would have a substantially uniform crosssection.

'Ihe edge of the blade is formed with rib or bulbous enlargement a on the rear face which extends from the root of the leafling portion A along the intermediate portion A2 to the tip of the discharge portion A3, and this rib may taper in width or deptl. or both along its length from front to rear.

The result of this construction of the blade l is to secure substantial freedom from cavitation along the rear face of the blade and, in conjunction with the varied pitch and channel area of the blade already described. it has the effect of drawing in the surrounding fluid centripetally towards the axis of the rotor along the forward portion of the blade, the inwardly moving fluid, as it were, lapping itself around the bulbous enlargement on the rear face of the blade, as indicated by the arrows in Fig. 1b to fill completely the channel formed between successive blades.

In Figs. 2 and 2a there is illustrated a centrifugal pump having an impeller similar in construction to the rotor shown in Fig. 1. that is to say it consists of a multiplicity of blades A wrapped spirally around the central boss B secured on the driving shaft D and with the boss forming fluid channels between successive blades of increasing area, in'so far as concerns the front portion of these channels, and of constant area in the rear or discharge portion thereof, the variation in the cross sectional area of the channels being determined by the increasing depth of the blades from the root of the leading' edge rearwardly. The blades, as before described, are formed with a rib or bulbous enlargement extending along their edge from the root of the front portion A along the intermediate portion A2 to the tip ofthe discharge portion A3.

The impeller is mounted to revolve within a fixed casing or inlet tank E of considerable capacity, so that the impeller rotates freely in a large volume of-water as an open-bladed unshrouded structure, into the channels of which the water is drawn from all sides by the action of the blades, these channels discharging the water throu h a ring of fixed deiector blades F, shown 1n development 1n Fi 2, into an annular expanding channel G Iormed between a fixed conical boss H and discharge pipe I, in which annular expanding channel `the velocity of the stream is converted into pressure.

As shown, a by-pass circuit may be established by connecting the interior of the hollow core or yboss H with the highest oiut of the casing E on the suction side o the pump through a duct H in the core leading to a pipe J, thereby allowing air to be sucked in through the clearance space between the fixed ring of deflectors F and the discharge end-of the impeller to the region of lowest pressure in the water stream or flume. To reduce leakage the gap between the discharge I end of the lmpeller and the fixed ring of deflector blades is preferably encircled by a fixed sealing ring K which may extend over the rear portions of the impeller blades.

The pump shown in. Fig. 3 does not differ in any respect from that of Fig. 2, except with regard to the construction of the impeller which is of the type shown in Fig. 1,

that is to say it is of constant disc area and the variation in depth of the fluid channels between the blades A is determined entirely by the configuration of the boss B. The same reference characters are applied to corresponding parts ofthe constructions of Figs. 3 and 2, so that the description of the latter -applies also to-Fig. 3, except in the above mentioned respect.

In the pump diagrammatically illustrated in Figs. 4 and 4 the impeller is arranged to discharge the water stream or flume outwardly into a volute or snail diffuser L, the impeller being otherwise of the type shown-in dotted lines in. Fig. 1.

It is sometimes of advantage, particularly in pump impellers, to provide short addi.- tional b ades between the main blades of the impeller around the discharge portion thereof, and to facilitate the construction of such l an impeller, as shown in Figs. 5, 5a and 5',

only the front portions of the main blades A are cast with the boss B, andthe remaining portions of these blades, together with the intermediate short blades A, are cast upon a ring A which is made to lit upon and be secured to the rearward end of the boss B. The formation of these'intermediate blades with respect to the rib yor bulbous enlargement along their edge conforms with the construction of the main blades, and further, these intermediate blades may, like the main.

blades, be of increasing depth rearwardly.

Figs. 6, 6 and 6b show a construction of rotor or impeller in which the bulbous edges a of the rotor blades A are made hollow and their'. interiors or ducts aP communicate at their forward ends with the interior B0 of pose, and this cavity in the boss 4communicates through an axial duct D in the driving shaft D with a control valve (not shown in the drawings) which opens at a predetermined pressure to admit air through the passages described to the region in which the boss B which is made hollow for this purcavitation is liable to be set up, that is in rear Vj of the rotor or impeller blades.

Obviously, instead of the ed es of the rotor or impeller blades lying whol y or partly in the periphery of an imaginary cylinder, the construction of boss carrying the blades may be such that they lie wholly or part-ly in the periphery of an imaginary cone, and other structural modifications may obviousl be made without exceeding the scope o the present invention.

In the construction of pump impeller shown in Fig. 7 the blades A may be regarded as consistin solel of the bulbous rib or edge portion a o the b ades previously described, with no web portion connecting it with the boss, and these blades are` arranged substantially tangentially to the boss instead of projecting radially therefrom. Otherwise they are wrapped spirally around the boss in the manner already described leaving comparatively shallow channels between successive blades of increasing cross sectional area in the direction of travel of the fluid.

Having thus described the` nature of the said invention and the best means I know of carrying the same into practical effect, I claim 1. A pump or turbine comprising in combination an inlet tank or casing of relatively large capacity and an unshrouded impeller or rotor rotating in the o en water space within the casing, said impe er or rotor comprising blades wrapped spiral fashion around a central boss and forming fluid channels of increasing area, said bladesbeing of increasing pitch alon any desired length thereof whereby there 1s produced a centripetal flow of the surrounding iiuid towards the boss along the said desired length.

2. A pump or turbine comprising in combination an inlet tank or casing of relatively large capacity and an unshrouded impeller or rotor rotating in the open water space within the casing, said impeller or rotor comprising a plurality of blades wrapped spiral iso and of uniform depth and pitch relatively along a succeeding portion of their length in the direction of flow of the liquid.

4. A pump impeller or turbine rotor having fluid channels formed by blades wrapped spiral fashion around a central boss, the rear surfaces of the outer or edge portion of said blades being formed with a hulhous rib or protuberance along any desired portion or" their length.

5. A pump impeller or turbine rotor according to claim ly wherein the rear surfaces of the outer or edge portion of the blades are formed with e bulbous rio or protuberance along the Whole or any portion of their length.

6. ln a pump or the like, a diffuser ring and a rotor rotatable relatively to said ring, said reim* comprising a central 1Doss und blades extending spirally around said boss, each of seid blades having a bulbous rib or protuber- .ance along any desired portion of its length,

seid ribs being hollow to admit air between the discharge ends of the blades and the difiuser ring, whereby air will be drawn behind Lhe rear surfaces of the blades.

ln testimony whereof li have signed my name to this specification.

EDMUND SCOTT GUSTAVE BEES. 

